Chiang Mai J. Sci. 2008; 35(1) 69

Biosorption of Lead (II) and Copper (II) from AqueousSolutionWoranart Jonglertjunya*Department of Chemical Engineering, Faculty of Engineering, Mahidol University, Bangkok, Thailand.

* Author for correspondence; e-mail: egwjl@mahidol.ac.th

Received : 18 September 2007

Accepted : 5 October 2007

ABSTRACT

In this study, the potential of biosorption of heavy metal ions by corncob and the

natural fungi growing on corncob was investigated. Solutions containing lead (II) and copper

(II) ions were prepared synthetically in single component and the time required for attaining

biosorption equilibrium was studied. The effects of initial pH of heavy metal ions solutions

and biosorbent dosages in respective ranges of 4.0 to 6.0 and 150 to 350 g (wet weight) on

adsorption efficiency were also examined.Results showed the equilibrium time for biosorption

of lead and copper ions from the solution to be approximately 90 minutes. The optimum

initial pH for lead and copper adsorption by the natural fungi growing on corncob was 5.0.

Under these conditions, the biosorption of lead and copper ions solution was 4.29 and 1.76

mg metal/g dry biomass, respectively. When using corncob alone as control, the corresponding

values for the biosorption of lead and copper were 1.09 and 0.67 mg metal/g dry biomass,

respectively, at initial pH level of 5. The adsorption equilibrium data were adequately characterized

by both Langmuir and Freundlich equations. The maximum adsorption capacity based on the

Langmuir isotherm, was found to be 14.75 and 1.77 mg metal per g dry weight biosorbent

for lead and copper adsorption, respectively, at initial pH level of 5.0 by the natural fungi

growing on corncob.

Keywords: Biosorption, Wastewater Treatment, Heavy Metal Ions.

1. INTRODUCTION

Rapid industrialization has led to

increased disposal of wastewater into the

environment. This often exceeds the

admissible sanitary standards and results in the

adverse impact on aquatic environment and

consequently on human health. Wastewater

treatment has received greater attention over

the years due to the global awareness of the

environmental deterioration. However, the

application of various treatment techniques

needs to agree with the wastewater characteris-

tics. For example, the wastewater from food

and beverage industries mainly consists of high

organic compounds, which are commonly

found in microbiological treatment processes

such as activated sludge process. On the other

hand, metallurgical industry, electroplating and

metal finishing industries, tannery operations,

chemical manufacturing, mine drainage and

battery manufacturing are examples of the

Chiang Mai J. Sci. 2008; 35(1) : 69-81

www.science.cmu.ac.th/journal-science/josci.html

Contributed Paper

Eno-010

70 Chiang Mai J. Sci. 2008; 35(1)

industrial sources of heavy metals ions found

in wastewater. A variety of suitable methods

can be used for the removal of metal

pollutants from such liquid wastes, including

filtration, chemical precipitation, coagulation,

solvent extraction, electrolysis, ion exchange,

membrane process and adsorption. Ion

exchange and adsorption are the most

common and effective processes for the

removal of heavy metal ions [1]. However,

high operation cost and input of chemicals

often make these processes impractical and

result in further environment damage [2].

Treatment of effluents with heavy metals

following biotechnological approaches is

simple, comparatively inexpensive and friendly

to environment [2-4] Microbiological

processes are of significance in determining

metal mobility and have potential application

in bioremediation of metal pollution [5].

Bioleaching of heavy metals, biooxidation of

precious metal from ores, desulfurization of

coal and oil, and biosorption of metal ions

are examples of the wide variety of potential

applications of microorganisms in mining and

related fields [6, 7].

Biosorption is the uptake of heavy metal

and radionuclides from aqueous solution by

biological materials (i.e biosorbents) [8]. A

low cost sorbent is defined as one which is

abundant in nature, or is a by-product or waste

materials. Various waste biomaterials such as

grape stalk waste [1], green coconut shell

powder [9], chaff [2], and crab shell particles

[4] have been studied for the removal of heavy

metal ions from the effluents. In addition to

biomaterials, microorganisms have also been

used as metal sorbents. Bacteria, fungi, yeast

and algae have been reported to remove heavy

metals from aqueous solutions [10].

Fungi in particular have demonstrated

unique metal adsorption characteristics and are

easy to cultivate [11]. Living and dead cells of

fungi can be used for the removal of heavy

metal ions [12]. In related studies, metal

removal abilities of various species of fungi

have been investigated such as Phanerochaete

chrysosporium [13], Trametes versicolor [14],

Aspergillus niger [12], Phellinus badius [8], and

Aspergillus oryzae and Phizopus oryzae [11].

However, no previous study has reported the

application of natural fungi for wastewater

treatment purposes for heavy metal removal.

It is well recognized that natural fungi can be

easily grown in substantial amounts on

biomaterial waste. Thus, there is potential for

utilizing some vegetable wastes as alternative

low cost metal sorbents. Corncob is one of

such wastes generated in the community, which

has been satisfactorily used for growing natural

fungi. Therefore, a fungal biomass growing

on corncob could serve as an economical

means for the removal of metal ions from

aqueous solutions.

The objective of this study was to

investigate the potential of corncob and the

natural fungi growing on corncob for

absorbing lead (II) and copper (II) from

aqueous solution. Also the influence of

various parameters such as adsorption

equilibrium contact time, initial pH and

amount of biosorbent on adsorption potential

of corncob was studied in detail.

2. MATERIALS AND METHODS

2.1 Biosorbent Preparation

Yellow corn on the cob was boiled in

filtered water at 100°C for 30 minutes, and

then corn was removed from corncob. Boiled

corncob was next cut into cubical pieces of

about 1.3 centimeter. All experiments were

carried out in 1.5 liter round plastic drinking

bottles containing corncob. The gas supply

system was designed to accommodate

ambient air through cotton wool. Based on

the results obtained from cell dry weight of

the natural fungi growing on corncob, the

bottles were incubated outside the building

Chiang Mai J. Sci. 2008; 35(1) 71

under the shade for 7 days for optimal growth.

The control experiments were set up by

preparing a series of bottles with the same

composition with no fungi present.

2.2 Copper (II) and Lead (II) Solutions

The chemicals used for the study were

analytical grades lead nitrate (Pb(NO3)

2) and

copper sulphate (CuSO4) purchased locally

from BDH company, Bangkok. The copper

(II) and lead (II) solutions with concentration

of about 1000 mg/l were prepared by

dissolving the respective amounts in distilled

water. The exact heavy metal content of the

solutions was analyzed by an atomic

absorption spectrophotometer (AAS).

2.3 Equilibrium Contact Time

All experiments were carried out in 1.5

liter round plastic bottles containing 350 g (wet

weight) of corncob to serve as control.

Another identical plastic bottle contained

similar amount of corncob with fungi

growing on it naturally. Each bottle contained

0.5 liter of the copper (II) and lead (II)

solutions with concentration of about 1000

mg/l. The initial pH levels of heavy metal ions

solution were adjusted to 4.0, 5.0 and 6.0.

Duplicate trials were conducted in all tests. For

analysis, 5 ml sample was taken out from each

bottle at regular time intervals of 30, 60, 90,

120, and 150 minutes. The heavy metal ions

solution was passed through a filter paper

(Whatman No. 1) to separate solid and liquid

phases and the filtrate was used for analyzing

the copper and lead concentrations.

2.4 Effects of Initial pHs on Adsorption

Capacity

All experiments were conducted in

duplicate in a 1.5 liter round plastic bottles

containing 250 g (wet weight) of corncob

with and without natural growth of fungi.

Each bottle contained 0.5 liter of the copper

(II) and lead (II) solutions with concentration

of about 1000 mg/l. Three different level of

initial pH (4.0, 5.0 and 6.0) were maintained

in the solution. All samples were taken at

optimal equilibrium contact time and filtered

as described in previous section. The filtrate

was subsequently analyzed for copper and lead

concentrations. The solid part was dried at

60 oC until reaching a constant level and

recorded as dry weight.

The metal concentrations adsorbed on

the solid were calculated from the difference

between heavy metal ions content (in mg per

liter) in the liquid solution before (Ci) and after

adsorption (Ceq

). The following equations

were used to compute the adsorption

percentage (%Ad) and the absorption capacity

by the adsorbent, qeq

(mg metal per g dry

biosorbent), respectively:

100% ×⎥

⎦

⎤⎢⎣

⎡ −=

i

eqi

C

CCAd (1)

)

w

V)(CC(q eqieq −= (2)

where V (in liter) is the solution volume and

w (in gram) the amount of dry biosorbent

used.

2.5 Effects of Biosorbent Dosage on

Adsorption Capacity

The experimental procedure described

in the previous section was followed using

different amounts of corncob (150, 200, 250,

300 and 350 g wet weight) and optimal initial

pH level. The samples were taken out for

analysis at optimal equilibrium contact time.

The data was then used to compute %Ad,

and qeq

(mg metal per g dry biosorbent).

2.6 Analysis of the Copper (II) and Lead

(II) Concentration

Copper and lead contents in the solution

72 Chiang Mai J. Sci. 2008; 35(1)

were determined by an atomic absorption

spectrophotometer (AAS). Calibration curves

for each metal were determined using

standardized metal solutions. The solutions

were diluted with distilled water and later the

same day the amounts of copper and lead

were determined by AAS (3300 Perkin

Elmer).

3. RESULTS AND DISCUSSION

3.1 Equilibrium Contact Time

Adsorption equilibrium is defined as the

equilibrium distribution of a given component

between an adsorbate and adsorbent. The

equilibrium adsorption isotherm data can be

characterized by a model such as the Langmuir

equation.

meqm qbCqq

111+= (3)

where: q is the concentration of adsorbed

metal per unit weight of biosorbent, Ceq

is

the concentration of heavy metal ions in the

liquid phase, qm

is the maximum adsorption

capacity per unit weight of biosorbent and b

is the adsorption equilibrium constant.

Equilibrium data for the bacterial adsorption

is plotted as 1/q vs 1/Ceq

, according to the

Langmuir isotherm. The two constants qm

and

b are calculated from the slope (1/qmb) and

intercept (1/qm) of the line, respectively.

The equilibrium isotherm data can also

be characterized by a model such as the

Freundlich equation.

n/eqKCq 1

= (4)

where: K and n are empirical constants

indicative of sorption capacity and sorption

intensity, respectively. The Freundlich

parameters were obtained by fitting the

experimental data to the linearized equation

(plot of log q against log Ceq

).

Figures 1 and 2 show the results on the

adsorption of lead (II) and copper (II) ions

from the solutions, respectively, at three

different initial pH levels. The heavy metal ions

concentration in the liquid-phase decreased

rapidly with time apparently due to the

adsorption of metal ions on the corncob and

finally leveled off. The results presented in

Figures 1 and 2 also showed that the amount

of adsorbed heavy metal ions was dependent

on the initial pH of the solution and the type

of biosorption media.

The initial sharp decrease in heavy metal

ions concentration in the liquid-phase implied

higher rate of biosorption (Figures 1 and 2).

The rate of biosorption was markedly

influenced by the levels of initial pH in the

solution. The overall results indicated that

the adsorption of heavy metal ions was

comparatively higher at initial pH of 5.0

irrespective of the presence of fungi on

corncob. The biosorption by the natural fungi

growing on corncob showed similar patterns

to corncob without fungal growth. The

reduction in heavy metal ion concentration in

the liquid phase resulting from the natural fungi

growing on corncob (Figures 1(b) and 2(b))

was much greater than the control experiments

(Figures 1(a) and 2 (a)). The adsorption of

heavy metal ions was enhanced by the

filamentous fungi present on the corncob

surfaces.

Adsorption of lead (II) and copper (II)

on corncob reached equilibrium levels both

in presence of natural fungal growth and

control samples as shown in Figures 1 and

2. Apparently, equilibrium adsorption levels

were attained after about 90 minutes of

exposure for all pH levels investigated in this

study. The data beyond 90 minutes indicated

only a little adsorption. The equilibrium

adsorption trends of copper (II) were in

good agreement with those of lead (II)

solution. The short equilibrium adsorption

contact time of about 90 minutes in lead (II)

Chiang Mai J. Sci. 2008; 35(1) 73

and copper (II) ions solutions in general agreed

with the other findings [4,14,15]. Taking into

account these results, a contact time of 90

minutes was chosen for further experiments

irrespective of initial pH level.

Figure 1. Biosorption of lead (II) ions as a function of time for (a) corncob alone and (b) in

the presence of natural fungi growing on corncob.

Figure 2. Biosorption of copper (II) ions as a function of time for (a) corncob alone and (b)

in the presence of natural fungi growing on corncob.

74 Chiang Mai J. Sci. 2008; 35(1)

3.2 Effects of initial pHs on adsorption

capacity

The pH of metal solution has been

identified as one of the most important

variables governing the biosorption process.

Based on the finding of optimum pH levels

in several studies [1,8,12-14,16] the range of

pH selected in this study was between 4

and 6.

The absorption capacity and the

adsorption percentage of lead (II) and copper

(II) ions solutions for different initial pH levels

are shown in Figures 3 and 4, respectively.

The adsorption capacity of lead (II) ions in

case of control corncob sample

(Figure 3) increased slightly with

increasing initial pH from 0.8 to 1.3 mg metal

per g dry weight biosorbent with

corresponding adsorption percentage ranging

from 23 to 38, respectively. The adsorption

capacity of lead (II) ions by the natural fungi

growing on corncob was relatively higher in

the range of 2.0 to 2.6 mg metal per g dry

weight biosorbent corresponding to the

adsorption percentage of about 67 to 77,

respectively. The optimum initial pH for lead

adsorption by the natural fungi growing on

corncob was found to be 5.0.

Figure 3. Comparison of the absorption capacity (q) and the adsorption percentage (%Ad)

of lead (II) ions by corncob alone and in the presence of natural fungi growing on

corncob for different initial pH levels.

The adsorption capacity of lead (II) ions

solution in the presence of fungi was much

greater than the control experiments. The

natural fungi growing on corncob at initial pH

5 resulted in the maximum adsorption capacity

of 2.6 mg metal per g dry weight biosorbent

in lead (II) solution as compared to about 0.9

mg metal per g dry weight biosorbent by the

corncob alone. This clearly demonstrated that

an increase in the adsorption capacity of lead

(II) ions because of the influence of fungi.

As shown in Figure 4, no significant

Chiang Mai J. Sci. 2008; 35(1) 75

difference was found in the values of the

absorption capacity and percentage in case of

copper (II) ions solution by corncob. The

adsorption capacity in copper (II) ions solution

was found to be about 0.6, 0.6 and 0.7 mg

metal per g dry weight biosorbent

corresponding to the same adsorption

percentage of about 19 for initial pH level of

4.0, 5.0 and 6.0, respectively. Although the

effect of initial pH on metal adsorption in

the control experiments was not significantly

different, it had a noticeable effect in the

presence of the natural fungi growing on

corncob. The corncob with fungi showed

adsorption capacity of copper (II) ions to be

1.0, 1.2 and 0.7 mg metal per g dry weight

biosorbent corresponding to the adsorption

percentage of about 34, 38 and 24 for initial

pH of 4.0, 5.0 and 6.0, respectively. Thus,

the optimum initial pH of 5.0 for copper

adsorption by the natural fungi growing on

corncob was found to be similar to the case

of lead (II) adsorption.

Overall results indicated the adsorption

capacity of copper (II) ions solution to be

very low in comparison to that of lead (II)

adsorption experiments in case of both

biosorbents. This may be probably due to the

difference in natural affinity between the type

of heavy metal and biosorbent. A direct

comparison of these findings is not possible

with the values reported in literature due to

different study conditions, metal ions and

fungus strains used in various studies.

However, the results on the adsorption of

lead (II) and copper (II) ions are in agreement

with the previous studies [12,14] by the live

cells showing comparatively higher adsorption

of lead (II) ions from the solution.

3.3 Effects of biosorbent dosage on

adsorption capacity

Biosorbent dosages may have a

significant influence on the adsorption capacity

and percentage. Vijayaraghavan et al. [4] found

that the percentage of copper and cobalt

removal by crab shell particles increased with

increase in biosorbent dosage, however,

biosorption efficiency (mg metal per g

biosorbent) decreased with increase in

biosorbent dosage. The small number of

published papers available does not allow

researchers to draw a sound conclusion; the

present study may contribute to fill this

apparent gap in knowledge.

Figure 4. Comparison of the absorption

capacity (q) and the adsorption

percentage (%Ad) of copper (II)

ions by corncob alone and in the

presence of natural fungi growing

on corncob for different initial pH

levels.

76 Chiang Mai J. Sci. 2008; 35(1)

Figure 5. Comparison of the absorption capacity (q) and the adsorption percentage (%Ad)

of lead (II) ions by corncob alone and in the presence of natural fungi growing on

corncob for different biosorbent dosages.

Figures 5 and 6 present typical set of

results obtained by varying biosorbent

dosages from 150 to 350 g (wet weight)

during lead and copper biosorption,

respectively. The adsorption of lead (II) ions

by the corncob (Figure 5) showed only a little

change in the value of q ranging from 1.23 to

0.78 mg metal per g dry weight biosorbent.

In addition, the percentage adsorption of lead

(II) ions by the corncob increased from about

20 to 44 % when the biosorbent dosage was

increased from 150 to 350 g.

In contrast, the adsorption of lead (II)

ions by the natural fungi growing on corncob

as shown in Figure 5 was markedly decreased

from 4.3 to 2.0 mg metal per g dry weight

biosorbent with an increase in biosorbent

dosage from 150 to 350 g. However, an

increase in the adsorption percentage of lead

(II) absorption from about 75 to 84 % by the

natural fungi growing on corncob appeared

to be gradual with a corresponding increase

in biosorbent dosage from 150 to 350 g.

The changes in the adsorption of copper

(II) ions followed the trends similar to lead

(II) ions as shown in Figure 6. The absorption

capacity of copper (II) ions by corncob alone

indicated a mean value of about 0.64 mg

metal per g dry weight biosorbent for two

replications and different dosages of

biosorbent. However, there was a decrease

in the absorption capacities of copper (II) ions

in case of the natural fungi growing on

corncob when biosorbent dosage increased

from 150 to 350 g. For 150 g of corncob

with the natural fungi, there was approximately

a two-fold decrease in the copper adsorption

as compared to 350 g of the same biosorbent.

Chiang Mai J. Sci. 2008; 35(1) 77

Figure 6. Comparison of the absorption capacity (q) and the adsorption percentage (% Ad)

of copper (II) ions by corncob alone and in the presence of natural fungi growing

on corncob for different biosorbent dosages

An increase in adsorption percentage was

observed in both experiments. The

adsorption percentage increased from 12 to

28 % for corncob used as control and from

27 to 43 % for the natural fungi growing on

corncob. These results are in good agreement

with Vijayaraghavan et al. [4] who reported

overall similar trends in an increase in the

adsorption percentage with increasing

biosorbent dosage despite the different type

of biosorbent. The highest adsorption

percentage of about 43 % was achieved for

350 g of corncob with natural fungal growth.

In general, the absorption capacity and

the adsorption percentage for copper (II)

solution were much lower than those of lead

(II) solution. This was an approximately two-

fold decrease in the copper adsorption

compared to the lead adsorption. Again, the

nature of biosorbent particles might have

played an important role in the adsorption

of different metal ions.

The equilibrium adsorption isotherms

data for lead and copper by the natural fungi

growing on corncob at initial pH of 5.0 are

characterized in Figures 7 and 8, respectively,

based on Equations 3 and 4 when the

biosorbent dosage varied between 150 and

350 g. For each biosorbent dosage, the

concentration of adsorbed metal per unit

weight of biosorbent (q) and the

concentration of heavy metal ions in the liquid

phase (Ceq

) were determined for equilibrium

time of 90 minutes. The equilibrium data for

78 Chiang Mai J. Sci. 2008; 35(1)

the lead adsorption was plotted as 1/q vs 1/

Ceq

, and log q vs log C

eq, according to

Equations 3 and 4, respectively. Subsequently,

the equation parameters for Langmuir

equation (qm and b) and Freundlich equation

(K and n) were determined from the slope

and intercept of the least-squares fits. Similar

analysis was carried out to determine

parameters (qm, b, K and n) for copper

adsorption from the plots of equilibrium data

as shown in Figure 8.

Figure 7. Plots for determining the parameters of Langmuir and Freundlich equations for

the adsorption of lead (II) ions by natural fungi growing on corncob (solution pH

5.0).

Figure 8 .Plots for determining the parameters of Langmuir and Freundlich equations for

the adsorption of copper (II) ions by the natural fungi growing on corncob (solution

pH 5.0).

Table 1 presents the results of regression

analysis for determining the parameters of

Langmuir and Freundlich equations (Equations

3 and 4). The coefficient of determination

(R2) ranged from 0.70 to 0.74 and 0.88 to

0.91 for adsorption of lead and copper,

respectively. These results indicated that the

equilibrium adsorption data of lead and

copper conformed reasonably well to the

Langmuir and Freundlich equations. Table 2

presents a general comparison of the results

of this study with other published work for

adsorption of lead and copper by different

fungal species. In particular, there is reasonable

agreement with the work of Kapoor et al.

[12] and Yetis et al. [13] Yan and Viraraghavan

[16 ].

Chiang Mai J. Sci. 2008; 35(1) 79

Table 1. Regression parameters of Langmuir and Freundlich equations for biosorption of

lead and copper by the natural fungi growing on corncob at initial pH of 5.0.

Langmuir equation Freundlich equation

Metal qm (mg metal K (mg metal per g

adsorption per g dry b R2 dry weight n R2

weight biosorbent)

biosorbent)

lead 14.75 7.03 x 10 -4 0.7417 2.39 x 10 -3 0.77 0.7037

copper 1.77 6.92 x 10 -4 0.8816 2.40 x 10 -5 0.59 0.9107

Table 2. Comparison of the parameters of Langmuir and Freundlich equations reported in

literature.

Langmuir equation Freundlich equation

References Adsorbent Heavy

metal qm

b R2 K n R2

ions

[1] Aspergillus niger Pb 598.0 4x10-4 0.61 0.63 0.6 0.62

(Live cell)

NaOH pretreated Pb 10.19 7.8 0.81 8.27 7.19 0.97

Aspergillus niger

pH = 5 Cu 4.69 0.30 0.88 1.47 0.79 0.79

[14] Immobilized Trametes Pb 194.76 6.13x10-4 0.98 190.61 3.16 0.945

versicolor

(Live cell) Cu 104.85 6.11x10-4 0.908 45.12 2.98 0.984

[16] Mucor rouxii Pb 35.69 0.80 0.95 14.31 2.10 0.88

(Live cell)

Mucor rouxii Pb 25.22 0.87 0.86 10.73 2.50 0.80

(dead cell)

[8] Phellinus badius Pb 169.90 6.07 0.997 - - -

(Live cell)

[13] Phanerochaete

chrysosporium Pb 33.00 0.01 0.03 5.47 8.31 0.09

(Live cell)

This work The natural fungi Pb 14.75 7.03 x 10-4 0.74 2.39 x 10-3 0.77 0.70

growing on corncob

Cu 1.77 6.92 x 10-4 0.88 2.40 x 10-5 0.59 0.91

80 Chiang Mai J. Sci. 2008; 35(1)

The parameters in Langmuir and

Freundlich equations (qm, b, K and n) have

been reported to depend on several factors

such as the experimental conditions, types of

metal ions and fungus strains used as

biosorbents. Specifically, the values of both

qm

and K in case of lead adsorption were

significantly higher than in copper adsorption,

which agrees with the findings of other

researchers. Also the decrease in the values of

qm and K for copper adsorption could be

explained by the lower affinity due to the

nature of biosorbent.

4. CONCLUSION

Adsorption of lead (II) and copper (II)

in the presence of natural fungi growing on

corncob attained equilibrium after about 90

minutes of exposure for initial pH ranging

from 4.0 to 6.0. The optimum pH level for

lead and copper adsorption by the natural

fungi growing on corncob was found to be

5.0. The overall adsorption percentage

increased with an increase in the biosorbent

dosage, but the biosorption efficiency (mg

metal per g biosorbent) was decreased.

Results showed maximum adsorption

capacity per unit dry weight of biosorbent

based on Langmuir isotherm to be 14.75 and

1.77 mg metal per g dry weight biosorbent

for lead and copper adsorption, respectively,

by the natural fungi growing on corncob.

ACKNOWLEDGEMENTS

I wish to thank the Faculty of

Engineering, Mahidol University for the

project grant. This work was supported by

the equipment in the Department of Chemical

Engineering, the Faculty of Engineering,

Mahidol University.

REFERENCES

[1 Marti•nez, M., Miralles, N, Hidalgo, S.,

Fiol, N., Villaescusa, I., and Poch, J.,

Removal of lead (II) and cadmium (II)

from aqueous solutions using grape stalk

waste. Journal of Hazardous Materials, 2006;

B133: 203-211.

[2] Han, R., Zhang, J., Zou, W., Xiao, H., Shi,

J., and Liu, H. Biosorption of copper

(II) and lead (II) aqueous solution by chaff

in a fixed bed column. Journal of

Hazardous Materials, 2006, B133: 262-268.

[3] Pal, A., Ghosh, S, and Paul, A.K.

Biosorption of cobalt by fungi from

serpentine soil of Andaman. Bioresource

Technology, 2006, 97: 1253-1258.

[4] Vijayaraghavan, K., Palanivelu, K., and

Velan, M.. Biosorption of copper (II)

and cobalt (II) from aqueous solutions

by crab shell particles. Bioresource Technology,

2006, 97: 1411-1419.

[5] Umrania, V.V. Bioremediation of toxic

heavy metals using acidothermophilic

autotrophes. Bioresource Technology, 2006,

97: 1237-1242.

[6] Barrett, J., Hughes, M.N., Karavaiko, G.I.,

and Spencer, P.A. Metal extraction by

bacteria oxidation of minerals, 1993, New

York: Ellis Horwood.

[7] Ehrlich, H.L. Geomicrobiology, 1990, 2 nd

ed. New York: Marcel Dekker.

[8] Matheickal, J.T., and Yu, Q. Biosorption

of lead from aqueous solutions by

Phellinus badius . Minerals Engineering, 1997,

10: 947-957.

[9] Pino, G.H., Souza de Mesquita, L.M.,

Torem, M.L., and Pinto, G.A.S.

Biosorption of cadmium by green

coconut shell powder. Minerals Engineering,

2006, 19: 380-387.

[10] Kapoor, A., and Viraraghavan, T. Fungal

biosorption-An alternative treatment

option for heavy metal bearing

wastewaters: A review. Bioresource

Technology, 1995, 53: 195-206.

Chiang Mai J. Sci. 2008; 35(1) 81

[11] Huang, C., and Huang, C.P.. Application

of Aspergillus oryzae and Rhizopus oryzae

for Cu (II) removal. Water Research, 1996,

30: 1985-1990.

[12] Kapoor, A., Viraraghavan, T., andCullimore, D.R.. Removal of heavymetals using the fungus Aspergillus niger.Bioresource Technology, 1999, 70: 95-104

[13] Yetis, U., Dolex, A., Dilek, F.B., andOzcengiz, G.. The removal of Pb (II) byPhanerochaete chrysosporium. Water

Research, 2000, 34: 4090-4100.

[14] Bayramoðlu, G., Bektas, S., and Arica,M.Y. Biosorption of heavy metal ions on

immobilized white-rot fungus Trametes

versicolor. Journal of Hazardous Materials,2003, B101: 285-300.

[15] Lodeiro, P., Barriada, J.L., Herrero, R.,and Sastre de Vicente, M.E. The marinemacroalga Cystoseira baccata as biosorbentfor cadmium (II) and lead (II) removal:Kinetic and equilibrium studies.Environmental Pollution, 2006., 142: 264-273.

[16] Yan, G., and Viraraghavan, T. Heavy-metal removal from aqueous solution byfungus Mucor rouxii, Water Research, 2003,37: 4486-4496.